Leak proof re-closable flexible pouch

ABSTRACT

The invention provides for a slider for a leak proof slider-zipper assembly having a leading edge and a trailing edge comprising a pair of protrusions at the bottom of the leading edge, a pair of protrusions at the bottom of the trailing edge, and an opening plow protruding from the top surface of the slider, between the leading edge and trailing edge, and having height not more than the height of the slider. The opening plow has a sloping surface from the leading edge towards the trailing edge such that the height of the opening plow at the leading edge is less than the height of the opening plow at the trailing edge.

The invention relates to a leak proof re-closable bag. More particularlythe invention relates to a leak proof flexible pouch with a sliderzipper.

BACKGROUND OF THE INVENTION

The use of re-closable flexible pouches has seen dramatic increase inthe last few years. Heretofore the primary market for bags with sliderzippers has been consumers who purchase empty slider bags and then fillthe slider bags with products at home. However, with the increasingpopularity of slider bags most manufacturers now tend to package theirfood and non-food products in slider bags for sale to consumers. Theslider bags are a great convenience to the consumer who purchases theseproduct filled bags especially for products of the type where only aportion of the product is used at any given time. The productapplications for which slider bags may be used are virtually unlimited.

Plastic bags having zipper closures typically consist of twosubstantially similar sized sheets of plastic film (usually suppliedfrom a pair of continuous web spools or rolls) which are then sealedtogether at a lower end of the sheets to form a front layer and a rearlayer, with the seal forming a bottom edge of the bag. Alternatively,the plastic bag may be formed by a length of bag film folded upon itselfto form a front layer and a rear layer connected by an integral bottomedge defined by the fold. Side edges of the plastic bag are typicallysealed using a sealing head.

The typical slider bags that are being manufactured are airtight as faras solids and powders are concerned. However, the bags are neither leakproof nor drip free where liquids are concerned. The problem of leakageis two fold in that leakage occurs due to the improper sealing of theside edges and also due to improper design of the slider and zipper.

The zipper closure itself is airtight along its length due to thereleasable and reusable seal formed by the inter-locked profile. A longstanding problem in the art of zipper sealed plastic bags however hasbeen the presence of escape gaps which are created during heat sealingat the outermost edges (such as at the bags two side seal locations) ofthe zipper closure. A drawback of such a method of sealing is the escapegaps that are formed at the intersection of the zipper closure, the bagfilm, and the side edges of the plastic bag. These escape gaps arefrequently formed as a result of applying continuous pressure and heatto seal the side edges of the bag, without making accommodations for theunderlying zipper closure that is typically already sealed along the topedge of the bag film. Such escape gaps facilitate leakage of air and/orliquid directly into or out of the contents of the plastic bag, whichcan cause undesired spillage, contamination and spoilage of suchcontents.

U.S. Pat. No. 3,986,914 and U.S. Pat. No. 6,033,113, incorporated herein totality by reference, address this problem and have provided methodsof overcoming this drawback. U.S. Pat. No. 3,986,914 provides for aplastic bead seal at the junction of the interlocking fastener and theside edges of the container. The plastic bead seal formed by a pressurebar, acts as a barrier to the passage of fluids or contaminatingbacteria through the fastener at this junction. One drawback of themethod of providing bead seals is that the bead seals are formed as aseparate step in the manufacturing process. Also, the pressure bar withthe specially configured channel is not found on conventional bag makingmachinery.

U.S. Pat. No. 6,033,113 provides for a zipper closure that is providedwith fillets along the uppermost and lowermost interlocking fingers ofthe zipper to prevent escape gaps from forming between the two sides,especially at the bags side seal locations. Conventional heat dies areused in combination with excess quantities of plastic material to formthe fillets. The method of fillets involves the use of extra plasticmaterials for the fillets.

To overcome this problem of escape gaps in particular at the side edges,the invention provides for the use of a sealing head with grooves madeon their inner surfaces such that excess material may flow into thegrooves of the sealing head and not result in escape gaps being createdduring the cooling stage. This may be better understood with referenceto FIG. 16, wherein the grooved edges are shown (35).

The slider device typically includes a separator or plow-type structurein the middle, or at one end, that opens a zipper closure mechanismhaving male and female interlocking profiled elements or closureprofiles when the slider device travels in a first direction along thezipper closure. The sidewalls of the slider device are inwardly taperedfrom one end to the opposite end so that the sidewalls engage theclosure profiles and progressively move them into engagement to closethe re-closable package when the slider device is moved along the zipperclosure in a direction opposite to the first direction.

Re-closable packages that include a slider device to more easily openand close the profiles typically face problems in providing a liquidtight seal across the entire length of the zipper closure due to thefact that the slider includes a plow device used to separate the closureprofiles as the slider is moved along the length of the zipper closure.Thus a portion of the zipper closure beneath the plow remains open atall times. One way of solving this problem is to include a notch formedin the mating profiles above the inter-locking elements to define a homeposition for the slider when the package is in the completely closedposition. The notch formed in the profile typically receives the plowformed on the slider such that the profile can be closed on each side ofthe plow to create a continuous seal across the entire package.Typically, the plow of the slider device does not extend past theinter-locking elements such that the notch does not create an openingbetween the inter-locking elements formed on the closure profiles.

Although the notch formed in the mating profile on the closed end of there-sealable package is known, problems can occur in utilizing such anotch with a full-length plow. For example, during the formation of thenotch portions of the re-sealable package near the location of the notchcan be damaged which affects the performance of the package.

U.S. Pat. No. 4,890,935 describes a slider wherein a foam plastic gasketmaterial is positioned between the inter-locking profile elements of thezipper at the closing end of the pouch and sealed thereof. The oppositeend of the gasket material is free and extends into the space betweenthe profiles at the closing end of the bag. When the leading edge of theslider is brought into engagement with the gasket material a seal isformed thereby eliminating the gap which otherwise would form in thearea occupied by the free end of the gasket. A slider tab is alsoprovided on the slider to engage a hook at the end of the zipper closureto hold the slider in position and maintain the seal. This method thougheffective is not practical as the addition of the gasket material andhook not only increases costs but also involves an extra step inmanufacturing. Furthermore closing of the pouch involves an extra stepof hooking the slider tab to maintain the seal. These factors make thismethod unviable.

U.S. patent application 2004/0086206 provides for a seal region betweenthe flaps of the male and female closures, such that the seal extendstowards the center of the package from the edge and is of a pre-definedlength. This pre-defined length of the seal is greater than the lengthof the slider. The seal region therefore provides a fluid tight sealbetween the two sealed flaps and below the slider when the slider is inthe home position. Theoretically the method of preventing leakage at theends of the zipper as described by U.S. 2004/0086206 appears to meet itsobjective. However, experimentation has found that liquid tends to seepinto the gap between the seal and the zipper and leak out through thegap in the zipper profile at the end edge due to the plow. Further, themethod also involves the use of extra sealing material as well as anextra manufacturing step that adversely affects costs.

OBJECTS AND SUMMARY OF THE INVENTION

It is therefore an object of the invention to provide a re-closableflexible bag that is leak proof and drip proof.

It is an object of the invention to provide a slider for the zipper of are-closable bag that makes the bag leak proof.

It is an object of the invention to provide a leak proof re-closable bagwithout increasing the cost of the bag.

It is an object of the invention to provide a leak proof re-closable bagthat can hold solids, liquids and gases.

To meet the aforementioned and other objectives the invention providesfor a slider for a leak proof slider-zipper assembly having a leadingedge and a trailing edge comprising:

-   -   a pair of protrusions at the bottom of the leading edge,    -   a pair of protrusions at the bottom of the trailing edge, and    -   an opening plow protruding from the top surface of the slider,        between the leading edge and trailing edge, and having height        not more than the height of the slider.

The invention also provides for a re-closable flexible packagecomprising:

-   -   a pair of side panels joined along a first side edge and a        second side edge, the panels defining a mouth providing access        to a package interior,    -   a zipper closure positioned along the mouth of the package for        selectively opening and closing the package mouth, the zipper        including a first pair of inter-locking members and a second        pair of inter-locking members below it,    -   a slider for opening and closing the zipper closure having a        leading edge and a trailing edge, the slider having a pair of        protrusions at the bottom of the leading edge, a pair of        protrusions at the bottom of the trailing edge, and an opening        plow protruding from the top surface of the slider, between the        leading edge and trailing edge, wherein the height of the        opening plow is such that it penetrates only the first pair of        inter-locking members of the zipper closure.

BRIEF DESCRIPTION OF ACCOMPANYING DRAWINGS

The accompanying drawings illustrate the preferred embodiments of theinvention and together with the following detailed description serve toexplain the principles of the invention.

FIG. 1 illustrates a front-top perspective view of the slider inaccordance with the invention.

FIG. 2 illustrates a front-bottom perspective view of the slider inaccordance with the invention.

FIG. 3 illustrates a front view of the slider in accordance with theinvention.

FIG. 4 illustrates a back-bottom perspective view of the slider inaccordance with the invention.

FIG. 5 illustrates a top view the slider in accordance with theinvention.

FIG. 6 illustrates a bottom view of the slider in accordance with theinvention.

FIG. 7 illustrates schematic back view of the slider in accordance withthe invention.

FIG. 8 illustrates a zipper for a re-closable bag in accordance with theinvention.

FIG. 9 illustrates the slider mounted on a zipper in accordance with theinvention.

FIG. 10 illustrates the opening action performed by a conventionalslider zipper.

FIG. 11 illustrates the closing action performed by a conventionalslider zipper.

FIG. 12 illustrates the opening action performed by the slider zipper inaccordance with this invention.

FIG. 13 illustrates the closing action performed by the slider zipper inaccordance with this invention.

FIG. 14 illustrates the drawback of conventional slider zippers at theclosing home position of the slider.

FIG. 15 illustrates the slider in accordance with this invention at itsclosing home position.

FIG. 16 illustrates the position of the plow or central notch when theslider in accordance with this invention is at its closing homeposition.

DETAILED DESCRIPTION OF THE INVENTION

It will be understood by those skilled in the art that the foregoinggeneral description and the following detailed description are exemplaryand explanatory of the invention and are not intended to be restrictivethereof.

At the outset it would be appropriate to mention that leading edgerefers to the edge of the slider that leads when the slider is moved toclose the zipper. Similarly, trailing edge refers to the edge that leadswhen the slider is moved to open the zipper.

Through out the patent specification, a convention employed is that inthe appended drawings, like numerals denote like components.

To overcome the aforementioned drawbacks of the prior art the inventionprovides for a slider that has a plow (alternatively plough) thatextends only up to the first interlocking members of a zipper profile.The slider also has closing profiles at both leading and trailing edgesat the lower end, such that the bottom inter-locking members of thezipper are sealed irrespective of the direction of movement of theslider. This ensures that the bottom inter-locking members are sealed bythe slider profile and not opened by the plow, at the edges of thezipper profile thereby providing for a leak proof re-closable bag. Theinvention will now be explained with reference to the followingembodiment.

FIG. 1 illustrates a front-top perspective view of the slider (1) havinga top surface (2) in accordance with the invention. The slider has aleading edge (4) and a trailing edge (5). The leading edge (4) has apair of protrusions (6) at the bottom surface (3) of the slider. An openarea (8) is formed between the bottom protrusions (6) and the topsurface (2). The two sides of the zipper last pass through theseprotrusions and the open area (8) when the slider is moved along thezipper in the opening direction. The slider is also provided with agrooved outer surface (7) for better gripping. The grip enables firmholding of the slider even with wet hands.

Referring now to FIG. 2 a front-bottom perspective view is shown. Asshown the trailing edge (5) also has a pair of protrusions (10) at thebottom surface (3). An open area (9) is formed between the protrusions(10) and the top surface (2) of the slider. The two sides of the zipperlast pass through these protrusions and the open area (9) when theslider is moved along the zipper in the closing direction. As may beobserved, open area (9) at the trailing edge is smaller than the openarea (8) at the leading edge. This may be visualized better in FIG. 5that depicts the top of the slider, wherein the opening at (9) measuredas (X) is smaller than the opening at (8) measured as (Y). As can alsobe seen at the bottom surface (3) the gap between the protrusions at theleading edge and the trailing edge (a, b) is substantially the same.

FIG. 3 shows a central notch or plow (11) hanging down from the topsurface (2) of the slider (1). As shown, the plow (11) does not extendalong the full height of the slider. The plow height is such that itpenetrates only the first pair of interlocking members of the zipper, asexplained in detail below. The plow is positioned approximately at thecenter of the slider. It should be noted that the shape and position ofthe plow may be varied as per requirement, and the figure serves only todescribe an embodiment of the invention.

FIG. 4 illustrates a back bottom perspective view of the slider. As canbe seen, the trailing edge (5) has a pair of protrusions (10), distancebetween the protrusions being such that the two sides of the zipper whenmade to pass through these protrusions will be pressed against eachother and consequently sealed together. The trailing edge also has anopen area (9), width of the open area (9) being such that the two sidesof the zipper are not allowed to separate and the seal is maintained.

FIG. 6 illustrates a schematic bottom view of the slider in accordancewith the invention. As can be seen, the trailing edge (5) in addition tothe protrusions (10) at the bottom surface (3) also has protrusions (13)that extend substantially between the top and bottom surfaces. Theseprotrusions (13) may be better visualized in FIG. 3. The protrusions(13) serve to reduce the open area (9) at the trailing edge such thatthe two sides of the zipper are pressed against each other.

FIG. 7 illustrates a schematic back view of the slider showing thebottom protrusions (10) and the plow (11).

Referring now to FIG. 8 a zipper (15) in accordance with the inventionis shown. The zipper has two sides (16,17) having correspondinginter-locking profile elements (18,19). The zipper (15) is also providedwith intermediate profile elements (21) that serve to align the twosides (16,17) of the zipper. As can be seen the upper members ofinter-locking profile members (18,19) form a first or upper seal (22 a).Similarly, the bottom members of the interlocking profile members(18,19) form the second or lower seal (23 a). The zipper is alsoprovided with external projections (20) on both sides (16,17) of thezipper. These projections (20) serve to lock the slider onto the zipperand to prevent the slider from detaching from the zipper.

FIG. 9 illustrates a schematic of the slider (1) fitted on to zipper(15) in accordance with the invention. As can be seen projections (20)help retain the slider onto the zipper by providing a positive lock. Theopening plow (11) also extends only up to the first pair ofinter-locking members (22). Thus when the slider is made to move overthe zipper, the plow opens only the first seal (22 a) of theinter-locking members. The bottom seal (23 a) of the inter-lockingmembers is opened by virtue of the design, in that, once the upper pairof inter-locking members (22) is opened the lower pair tends to separatealso.

FIGS. 10 and 11 illustrate the conventional slider opening and closing azipper respectively. As can be seen from the figures the opening plowextends up to both the pairs of inter-locking members (22,23). Also theplow (11) has the same height throughout. The problem with thisconventional slider and plow is that at the closing edge the centralplow separates the two sides (16,17) of the zipper completely. Thisleads to small escape gaps between the zipper edge and the leading edgeof the opening plow through which leakage may occur. This may be betterunderstood by FIG. 14. As shown, the slider (1) is at its closing homeposition with the leading edge in touch with the sealed edge of the bag.The edges of the bag are sealed (30) along with the two sides (16,17) ofthe zipper. In the expanded view box, as shown, the two sides of thezipper (16,17) are separated by the opening plow (11). This results inthe formation of minute gaps (31) between the tip of the opening plow(11) and the edge of the seal (30).

FIG. 12 illustrates the opening action performed by the slider zipper inaccordance with this invention. As can be seen from the figure, slider(1) is moving towards the left to open the zipper (15). The opening plow(11) in accordance with the invention has a longer edge (11 a) and ashorter edge (11 b). The opening plow (11) has a height such that itonly penetrates the first or upper pair of inter-locking members (22).Accordingly, the longer edge first passes through first pair ofinterlocking members (22) and opens the seal.

The opening mechanism may be explained as follows:—

During the opening action, the leading edge (4) of the slider followsthe trailing edge (5). The trailing edge has bottom protrusions (10) andopen area (9), both which ensure that the two sides of the zipper(16,17) remain pressed against each other. Thus when the slider is movedover the zipper in the opening direction, the two sides (16, 17) of thezipper that first pass through the trailing edge are sealed and both thepairs of inter-locking members (22,23) are locked. The two sides (16,17)then encounter the opening plow (11), wherein the first pair ofinter-locking members (22) are opened by the longer edge (11 a) of theplow (11). The opening plow (11) however does not open the bottom pairof inter-locking members (23). When the slider is moved further ahead,the two sides of the zipper are made to pass through the leading edge(4) of the slider. The leading edge (4) has protrusions (6) at thebottom and an open area (8). On passing through the leading edge, theopen area (8) of the slider is such that the opened first pair ofinter-locking members (22) are kept open. The protrusions (6) of theleading edge keep the bottom or lower pair of inter-locking members (23)locked. Thus on leaving the leading edge (4) the upper pair (22) is openwhereas the bottom pair (23) is locked. However, by virtue of the designand flexibility of the material used for the zipper, the open upper pair(22) causes the lower pair (23) also to open thereby opening the zipper.

FIG. 13 illustrates the closing action performed by the slider zipper inaccordance with this invention. As can be seen from the figure, slider(1) is moving towards the left to close the zipper (15). The openingplow (11) has a height such that it only penetrates the first or upperpair of inter-locking members (22), and has a longer edge (11 a) and ashorter edge (11 b). In accordance with the invention the shorter edge(11 b) first passes through first pair of interlocking members (22).

The closing mechanism may be described as follows:

During the closing action, the trailing edge (5) of the slider followsthe leading edge (4). The leading edge has bottom protrusions (6) andopen area (8). The protrusions (6) ensure that the two sides of thezipper (16,17) remain pressed against each other at the lower pair ofinter-locking members (23). Thus when the slider is moved over thezipper in the closing direction, the two sides (16, 17) of the zipperfirst pass through the leading edge, the lower or bottom pair ofinter-locking member (23) is locked, while due to the substantiallylarger open area (8) the upper pair of inter-locking members (22) remainopen. The two sides (16,17) then encounter the opening plow (11),wherein the first pair of inter-locking members (22) is kept open by thelonger edge (11 a) of the plow (11). The opening plow (11) however doesnot open the bottom pair of inter-locking members (23). When the slideris moved further ahead, the two sides of the zipper are made to passthrough the trailing edge (5) of the slider. The trailing edge (5) hasprotrusions (10) at the bottom and an open area (9). On passing throughthe trailing edge, the open area (9) of the slider is such that theopened first pair of inter-locking members (22) is now locked and thesealing is complete. The protrusions (10) of the trailing edge keep thebottom or lower pair of inter-locking members (23) locked. Thus onleaving the trailing edge (5) both the pairs of inter-locking members(22, 23) are locked giving a complete seal.

With reference now to FIG. 15, the slider (1) in accordance with theinvention is shown at its closing home position. The bag has its endssealed (35) as shown. At the closing home position, the leading edge (4)of the slider comes in contact with the end seal (35) and also partiallyoverlaps it. The opening plow (11) is also pressed against the end seal(35). As shown the shorter edge (11 b) of the opening plow is above theend seal and the longer edge (11 a) is penetrating the upper pair ofinter-locking members (22) of the zipper (15). The slanting edge of theopening plow thus completely seals the edge and eliminates the escapegaps that were formed with the sliders of the prior art. In addition tothis, as shown in FIG. 16, leading edge (4) of the slider with itsbottom protrusions (6) closes the lower pair of inter-locking members(23) at the edge near the end seal (35).

Therefore, though the opening plow (11) keeps the upper pair ofinter-locking members (22) open at the edge of the end seal (35,30), theprotrusions (6) keep the lower pair of inter-locking members (23) belowthe opened upper pair sealed.

Thus, the zipper when closed, is completely sealed along the bottom pairof inter-locking members (23) providing a leak proof and drip freere-closable flexible pouch, and the upper pair of interlocking members(22) are sealed throughout except at the end closing position, where theopening plow (11) penetrates the inter-locking members (22). The slopededge of the opening plow (11) ensures that there is no gap between theopening plow and the end seal (35). This again ensures a drip free andleak proof re-closable pouch at the upper pair of inter-locking membersalso.

It will readily be appreciated by those skilled in the art that thepresent invention is not limited to the specific embodiments hereinshown. Thus variations may be made within the scope and spirit of theaccompanying claims without sacrificing the principal advantages of theinvention.

1. A re-closable flexible package comprising: a pair of side panelsjoined along a first side edge and a second side edge, the panelsdefining a mouth providing access to a package interior; a zipperclosure having two sides positioned along the mouth of the package forselectively opening and closing the package mouth, the zipper closureincluding a first pair of inter-locking members on the two sides of thezipper closure and a second pair of inter-locking members on the twosides of the zipper closure disposed below the first pair ofinter-locking members; and a slider having a leading edge and a trailingedge configured to open and close the zipper closure, the slider havinga first pair of protrusions at a bottom of the leading edge, a secondpair of protrusions at the trailing edge, and an opening ploughprotruding downward from a top surface of the slider between the leadingedge and trailing edge, the opening plough having a height not more thana height of the slider such that the opening plough penetrates only thefirst pair of inter-locking members of the zipper closure, the openingplough having a sloped bottom surface such that a leading edge side ofthe opening plough has a height less than a height of a trailing edgeside of the opening plough, the leading edge side of the opening ploughremains above the first pair of inter-locking members when the slider isnear one of the first side edge and the second side edge of the pair ofside panels and the zipper closure is in a closed configuration.
 2. Are-closable flexible package as claimed in claim 1 wherein the zipperclosure has an external projection to lock the slider on to the zipperclosure.
 3. A re-closable flexible package as claimed in claim 1 whereinan edge seal of the package at the junction of the zipper closure andpackage is grooved.
 4. A re-closable flexible package as claimed inclaim 1 wherein a first open area is formed between a top surface of theslider and the first pair of protrusions.
 5. A re-closable flexiblepackage as claimed in claim 1 wherein an open area is formed between atop surface of the slider and the second pair of protrusions.
 6. Are-closable flexible package as claimed in claim 4 wherein a second openarea is formed between the top surface of the slider and the second pairof protrusions, the first open area being larger than a the second openarea.
 7. A re-closable flexible package as claimed in claim 1 whereinthe slider has a grooved surface configured to be grasped by a user. 8.A re-closable flexible package as claimed in claim 1 wherein a first gapis formed between the first pair of protrusions such that the two sidesof the zipper closure passing though the protrusions are sealed.
 9. Are-closable flexible package as claimed in claim 8 wherein a second gapis formed between the second pair of protrusions such that the two sidesof the zipper closure passing though the protrusions are sealed.
 10. Are-closable flexible package as claimed in claim 9 wherein the first gapand second gap are substantially the same dimensions.
 11. A re-closableflexible package as claimed in claim 1 wherein the opening plough has atrapezoidal profile.